Consult the company or Standard and Poor's Register of Corporations if in doubt about a formal name. Do not, however, use a comma before Inc. or Ltd.
Generally, follow the spelling and capitalization preferred by the company: eBay. But capitalize the first letter if it begins a sentence.
Do not use all capital letter names unless the letters are individually pronounced: BMW. Others should be uppercase and lowercase.
Do not use symbols such as exclamation points, plus signs or asterisks that form contrived spellings that might distract or confuse a reader. Use an ampersand only if it is part of the company's formal name, but not otherwise in place of "and."
Use "the" lowercase unless it is part of the company's formal name.
See the organizations and institutions entry.